Surgical instruments for minimally invasive surgery are increasingly relied upon to reduce the hospital stay and recovery time for various surgical procedures. Many of these surgical instruments include mechanisms that actuate an end effector via an elongate shaft that performs a surgical step that entails two opposing surfaces being brought into opposition to each other. For instance, pivotally opposed jaws are used in graspers. Pivotally attached scissor blades are incorporated into cutting devices. Providing an actuating control down the elongate shaft with sufficient strength is complicated by a design goal of minimum cross sectional area so as to pass through a small cannula of a trocar. In addition, the elongate shaft often has a plurality of control functions (e.g., rotation, articulation, etc.) Further, it is desirable to have reduced design complexity so as to provide an economical device.
As an illustration of a particularly challenging surgical instrument, surgical staplers have been used in the prior art to simultaneously make a longitudinal incision in tissue and apply lines of staples on opposing sides of the incision. Such instruments commonly include a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil.
An example of a surgical stapler suitable for endoscopic applications, described in U.S. Pat. No. 5,465,895, advantageously provides distinct closing and firing actions. Thereby, a clinician is able to close the jaw members upon tissue to position the tissue prior to firing. Once the clinician has determined that the jaw members are properly gripping tissue, the clinician can then fire the surgical stapler, thereby severing and stapling the tissue. The simultaneous severing and stapling avoids complications that may arise when performing such actions sequentially with different surgical tools that respectively only sever or staple.
These minimally invasive surgical instruments have been widely used and have proven to be a significant advance over traditional open surgical techniques. It would be desirable to incorporate yet additional features and capabilities.